Contribution of PowerPC port.

src/disassembler.cc

Index: src/disassembler.cc
diff --git a/src/disassembler.cc b/src/disassembler.cc
index d58e1b073f0f2a0a43eafafe2e65573904296ba0..53cb15c67ee9e9b3793ef3fa637b7ecf81be1063 100644
--- a/src/disassembler.cc
+++ b/src/disassembler.cc
@@ -107,11 +107,14 @@ static int DecodeIt(Isolate* isolate,
   } else {
     // No relocation information when printing code stubs.
   }
+#if !V8_TARGET_ARCH_PPC
   int constants = -1;  // no constants being decoded at the start
+#endif
 
   while (pc < end) {
     // First decode instruction so that we know its length.
     byte* prev_pc = pc;
+#if !V8_TARGET_ARCH_PPC
     if (constants > 0) {
       SNPrintF(decode_buffer,
                "%08x       constant",
@@ -136,6 +139,22 @@ static int DecodeIt(Isolate* isolate,
                  ptr - begin);
         pc += 4;
       } else {
+#elif ABI_USES_FUNCTION_DESCRIPTORS || V8_OOL_CONSTANT_POOL
+    // V8_TARGET_ARCH_PPC
+    {
+      // Function descriptors are specially decoded and skipped.
+      // Other internal references (load of ool constant pool pointer)
+      // are not since they are a encoded as a regular mov sequence.
+      int skip;
+      if (it != NULL && !it->done() && it->rinfo()->pc() == pc &&

[danno, 2014/07/29 13:24:08]

Again, please try to avoid non-boilerplate platform #ifdefs in shared code
whenever possible.

It seems like it would be cleaner to make everything in this if() a call to a
help function that is present on all platforms that also returns "false" on non
PPC (and thus falls through to the decode_buffer[...] code), and actually does
this heavy lifting on PPC.

[andrew_low, 2014/07/30 13:27:04]

I'm going to need a bit more help / detail here. Your comment appears to be
attached to line 149 in my modified version of the file. However, if we look
back on line 117 we can see #if !V8_TARGET_ARCH_PPC which seems like a bad idea.

I don't dis-agree with the idea of refactoring this. When developing the code,
we avoided changing the other sub-directories (implementations) and this caused
a bit more of a mess in common code.

Please be more specific in your refactoring / abstraction suggestion.

On 2014/07/29 13:24:08, danno wrote:

+          it->rinfo()->rmode() == RelocInfo::INTERNAL_REFERENCE &&
+          (skip = Assembler::DecodeInternalReference(decode_buffer, pc))) {
+        pc += skip;
+      } else {
+#else
+    {
+      {
+#endif
         decode_buffer[0] = '\0';
         pc += d.InstructionDecode(decode_buffer, pc);
       }